1500 won't start when warm

kmesse · Aug 25, 2016

1998 1500 - After driving 10-15mins, the truck won't start again. It barely cranks as if the battery was dead, but battery was tested fine, and 15 mins ago it started right up. If it cools down enough, it'll start right up again. All dash lights before trying to start. When trying, its like it takes every ounce of power - dash goes out, things click, clock resets.

What I've done:
Replaced the starter with a tested salvage yard starter
Replaced wiring to starter
tested battery
dug all over the internet for the problem
I added a heat wrap around it, that didn't help.
When it doesn't start, tested battery. Drops to 10-11v when trying to start.
Tried jumping with another battery, no effect.

?

Rlaf75 · Aug 25, 2016

1st off id recommend staying away from used parts. Now with that said. If the clock resets then it's a power issue or I should say a lack of power issue. I'd replace the battery with a NEW battery and clean the terminals to make sure it has good connections.

joepizuro · Aug 26, 2016

Long shot here but wonder if any wires are getting hot somewhere?

crash68 · Aug 26, 2016

Check the ground from the battery to the engine, if there isn't a dedicated wire add one.

Whiteram02 · Aug 26, 2016

Front diff seal

Front diff seal leaks on passenger side but only a

small puddle. Could it be the inner seal or the outer seal? I've read the outer one is just a dust gasket so does that mean the inner one is also busted?

dudeman2009 · Aug 26, 2016

Whiteram02 said:
Front diff seal leaks on passenger side but only a View attachment 76359small puddle. Could it be the inner seal or the outer seal? I've read the outer one is just a dust gasket so does that mean the inner one is also busted?

Dude come on, dont hijack threads.

yoda · Aug 26, 2016

If you have a volt meter, when truck is acting up, have someone try and crank engine, while doing a voltage drop test on your negative cable. (Put one end of the voltmeter on neg post of battery, the other end on the starter body.) If you are reading more than a .2 volts or so while trying to crank engine you have a ground problem

kmesse · Aug 26, 2016

I bought the battery last year and had it tested, it was good (whatever their test is). Voltmeter when it's cool: 13.8 sitting, 12.8 when I turn to acc, and 11.2 or something when I crank it.

It definitely sounds like power problem the way the lights pulse with each attempted crank, but not a battery problem. If it was battery, why would it work fine, 15 mins later not work, then work fine again when it cools down? I let it cool over night and it starts right up fine now with the above readings. Drops an extra volt when trying to crank it when its hot.

Question is what causes the power drop only when it's hot? Could anything internal in the gears do that to make it harder to crank? I'm tempted to think a wire gets hot also, but the Pos wire is well clear of things and the signal wire wouldn't make a difference. All battery terms are like new.

yoda · Aug 26, 2016

kmesse said:
I bought the battery last year and had it tested, it was good (whatever their test is). Voltmeter when it's cool: 13.8 sitting, 12.8 when I turn to acc, and 11.2 or something when I crank it.

It definitely sounds like power problem the way the lights pulse with each attempted crank, but not a battery problem. If it was battery, why would it work fine, 15 mins later not work, then work fine again when it cools down? I let it cool over night and it starts right up fine now with the above readings. Drops an extra volt when trying to crank it when its hot.

Question is what causes the power drop only when it's hot? Could anything internal in the gears do that to make it harder to crank? I'm tempted to think a wire gets hot also, but the Pos wire is well clear of things and the signal wire wouldn't make a difference. All battery terms are like new.

You need to verify the ground side of the circuit, there should be a large ground wire going from your battery to your engine block somewhere. Or use a set of jumper cables. when the truck is acting up put the ground of the jumper cables to the battery neg. clamp the other end directly to the engine block, or better yet the starter body.

kmesse · Aug 27, 2016

yoda said:
You need to verify the ground side of the circuit, there should be a large ground wire going from your battery to your engine block somewhere. Or use a set of jumper cables. when the truck is acting up put the ground of the jumper cables to the battery neg. clamp the other end directly to the engine block, or better yet the starter body.

Will try, and post results.

kmesse · Aug 27, 2016

yoda said:
You need to verify the ground side of the circuit, there should be a large ground wire going from your battery to your engine block somewhere. Or use a set of jumper cables. when the truck is acting up put the ground of the jumper cables to the battery neg. clamp the other end directly to the engine block, or better yet the starter body.

BRILLIANT, it was a ground! I jumpered straight from battery to the starter case, and it started right up. From battery to other bolts it didn't. So at the very least I know I can bandaid by adding a ground wire straight to the starter, but I'll have to track down all the grounds and see where the problem is. Chances are when I find it it'll fix some other things that were elusive.
THANKS! I'll try to post when I find where the actual issue lies. :happy107:

yoda · Aug 28, 2016

Glad you are getting to the bottom of your problem.
These type of electrical issues is where voltage drop tests come in so handy.
I try and teach younger techs to use it and It is confusing to allot of guys, especially on ground circuits.
My next step would be put one end of your voltmeter on battery neg. put the other end on the starter body(when it is acting up) have someone crank the engine. I am guessing you will see 3-4 volts. it should be 0.
Next move to the transmission case. If you have 0 volts at transmission case your problem is the starter is not making good contact to the transmission.(Corrosion loose bolts etc.) if you see the same voltage as at the starter you need to keep working your way back to the battery neg.Engine block so on, the most likely is where the main neg. battery cable eyelet bolts to the engine.

Hope that helps and not to confusing.

kmesse · Aug 28, 2016

Wow, I tested to starter case got beyond 9 volts. Next to it at engine block was zero. So I guess the connection is block to the starter! So I clean the contact area to bare metal and get new bolts and try again?

yoda · Aug 28, 2016

Yes, although the starter bolts to the transmission not the engine, check the transmission case for voltage just for the heck of it, unlikely all your bell housing bolts are loose and losing connection between engine and trans. but I've seen stranger things.
There would be nothing wrong with running a large dedicated ground from your battery to starter, but it would be a good idea to find the actual problem.

kmesse · Aug 28, 2016

Yes I meant where the starter attaches. I get 0 volts there, so I'll get new starter bolts and clean it up. if that doesn't help I'll do a dedicated wire and call it a day. Trying to save as much $ as possible.

yoda · Aug 28, 2016

yep, make sure the starter is clean bare metal, sandpaper or wire wheel, especially where the bolt head contacts the starter. I think it mainly grounds through the bolts, it would be hard to clean the trans bell housing and the dust shield that is sandwiched between the starter and trans. good luck

1500 won't start when warm

kmesse

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Rlaf75

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joepizuro

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crash68

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